As a tire wears, the volume of the tread decreases due to frictional contact with the road surface. As the tire wears, the volume of the grooves decrease, as the non-skid decreases. When the groove volume decreases, it reduces the tire's ability to channel water away from the tire footprint, reducing wet road tire performance. For some tread configurations, even if the tire tread has not worn down to the legal minimum non-skid depth, the tire's wet road performance may be severely limited.
It is thus desired to provide a tire having excellent wet and dry performance characteristics when new, and have acceptable wet and dry tire performance during its life.